Apparatus for heat treating steel stamp blanks



y 1942- L. D; DONBECK 2,290,546

APPARATUS FOR HEAT TREATING STEEL STAMP BLANKS Filed June 22, 1 940 [nowafar: zflem 0. DOA/BECK,

Patented July 21, 1942 UNiTE; S-TTES V APPARATUS FOR HEAT TREATING STEELSTAMPBLANKS Larry'D'. Donbeck, Gary, Ind. Application June 22, 1940,Serial No.341fl26 2 Claims. (01. 266-6) This invention relates toimprovements in apparatus for the quenching of steel articles to providethe same with both hardened and ductile portions.

For example, in the manufacture of steel stamps, it is customary toharden the blanks to .be -used therefor and to provide ductile end por-My invention contemplates the production of such steel articles havinthe desired hardened and ductile portions by apparatus enabling thecontrol of the formation of the ductile portions as to the extent anddegree thereof.

I further have in view the provision of apparatus capable of suchcontrolled treatment for a plurality of articles to produce the samewith a high degree of uniformity.

Additional objects and advantages will become apparent from thefollowing description taken in connection with the accompanying drawing,wherein:

Fig. 1 is a top plan view of a quenching fixture employed in thepractice of my invention;

Fig. 2 is a top plan view thereof; and

Fig. 3 is an enlarged detail section taken on the line III-III of Fig.1.

Referring to the drawing, a designates a series of steel stamp blanks orthe like whose shank portions are to be hardened and one terminalportion of each of which is to be rendered soft and ductile for thesubsequent cold working of the latter. The blanks a are preformed ofrectangular, square, round or other desired crosssection, and arepreferably of eutectoid or hypereutectoid steel containing fromsubstantially .85% to 1.10% carbon.

From the standpoint of commercial production as well as for uniformity,it is desirable to treat a plurality of the blanks a in a singleoperation, as for example, by heating and quenching a plurality thereofsimultaneously. In addition, it is desired to uniformly control thecooling of those portions of the blanks a which are to -be rendered softand ductile.

For these purposes, I provide aquenching 'fi-X- ture 5 comprising ametal body of convenient configuration. While I have shown the fixture.in the form of a ring, other shapes may be employed so long as theyembody the physical characteristics hereinafterset forth.

The quenching fixture 5 includes a plurality of sockets fi having aconfiguration corresponding to the cross-section of the-blanks a, andhavinga'dequate depth to receive and retain the ends of the series ofblanks with their shanks or major portions of their lengths freelyprojecting above the fixture.

The fixture -5 thus provides :anadded mass "of metal, such as steel,surrounding the end portion of each blank a, servin to influence therate of heat transfer from the blanks during quenching -of the -same,which influence'alfects the hardenability of the blanks. This'conditionor influence may be designated as a mass effect, by which I am enabledto produce the results and advantages desired in respect to controllingthe ductility of the end portions of the blanks, While permitting thehardening of their shank portions.

The sockets 6 containing the ends of the blanks a are spaced apart asufficient distance to provide a substantial mass of metal surroundingthe same, the spacing also being sufficient to permit free circulationof a quenching medium about the shanks of the blanks upon immersin thefixture and blanks in a quenching bath. Said spacing also prevents anyinterference with the quenching action due to the combined heatingeffect of adjacent blanks.

The fixture 5 and its contained blanks a are heated to a temperatureWithin the thermal critical range of the steel of the blanks, whichtemperature in the case of the eutectoid and hypereutectoid steelspreferred may be between approximately 1380 F. and 1450 F., and thefixture and blanks are then quenched together in cold water.

The rapid and unimpaired cooling of the free shank portions of theblanks a hardens the same to the desired degree of hardness, whereas themass effect of the fixture 5 retards the cooling of the inserted endportions of the blanks sufficiently to permit a direct transformation ofthe unstable austenite into pearlite, whereby said end portions willhave the desired ductility.

In other words, the mass effect of the fixture provides a time phaseduring the. cooling of the end portions of the blanks, permitting such atransformation to take place.

The foregoing method and apparatus permit positive and accurate controlof the ductility of the end portions of the blanks or articles beintreated, both as to the degree and extent of said ductility. Thus, themass effect of the fixture may be controlled by the mass or sizethereof, thereby controlling the time phase of the treatment and hencethe degree of ductility obtained. Also, the depth of the sockets 6 maybe varied to correspondingly vary the length or extent of the ductileportions produced.

These factors, together with the spacing of the sockets also provide foruniformity of the resulting product, both as to their hardened andductile portions. The said uniformity is also promoted by the ring formof the fixture, the same tending to a more uniform heating and coolingas well as providing uniformity of heat transfer between the pluralityof blanks and the fixture.

With further reference to the spacing and orientation of the sockets 6,I prefer to position sockets for blanks of rectangular or squarecrosssection in corner-to-corner relation, as shown in the drawing, thusminimizing the heating effect between adjacent blanks and insuringthorough and complete quenching throughout the free portions of theblanks.

For the purpose of furthering the control. of the characteristics ofhardness and ductility in the blanks by means of my invention, I preferto employ a steel of the type stated whose cementite is in spheroidizedform. While steel whose cementite is in either lamellar or spheroidizedform may be employed, I have found that the latter produces superiorresults for present purposes when heated and quenched in the manner setforth herein, the spheroidized form tending to a lower hardenability.

Spheroidized cementite tends to be more sluggish than the lamellar formin going into solid solution, and since the cold workability of thesteel is enhanced by not throwing all the carbon into solid solution,the said form enables the production of a high degree of ductility bythe present heat treatment. Further, it is thought that a steel whosecementite has been spheroidized is more adaptable to the control factorsapplied by the present invention.

Suitable means may be employed for immersing and withdrawing thequenching fixture 5. For example, I designates a supporting spiderhaving a lifting eye 8 projecting therefrom and above the fixture.

Various changes and modifications are contemplated within the scope ofthe following claims.

I claim:

1. A quenching fixture for the heat treating of rectangular high carbonsteel stamp blanks including a metallic ring having an annular series ofsockets therein of rectangular cross-section and arranged incorner-to-corner relation, said sockets being equally spaced within theconfines of the ring and spaced apart to provide a sufficient mass ofthe ring about each socket to uniformly control and retard the rate ofheat transfer from those portions of the stamp blanks enclosed by thesockets, upon heating the blanks and fixture and then quenching the samewith the blanks in said sockets.

2. A quenching fixture for the heat treating of high carbon steel stampblanks and the like, including a unitary metal body having a series ofspaced sockets therein for receiving and enclosing the end portions ofsaid blanks and the like, the spacing of all of the sockets with respectto the confines of the body and with respect to each other providing amass of the metal of the body about each socket to eifect asubstantially uniform retarded cooling of the blank end portions in eachof said sockets upon heating and then quenching the blanks and fixturetogether.

LARRY D. DONBECK.

